Immersion type heater



May 10,1966 G. w. OKERSTROM IMMERSION TYPE HEATER Filed Dec. 17', 1963 United States Patent 3,251,017 IMMERSION TYPE HEATER Gilbert W. Okerstrom, Minneapolis, Minn., assignor to Phillips Manufacturing Company, Inc, Minneapolis, Minn, a corporation of Minnesota Filed Dec. 17, 1963, Ser. No. 331,200 Claims. (Cl. 338-229) This invention relates to immersion type heaters and more particularly to an improved immersion type heater that is eflicient in operation, inexpensive to manufacture and rugged in construction.

Immersion type heaters are normally applied or used in the heating ofa fluid under abnormal temperature conditions of a fluid and have found their primary use in raising the temperature of crank case oil in internal combustion engines in cold weather. They are normally a device utilized on intermittent basis and selectively insertable into the fluid to heat the fluid rather than be normally positioned at all times in the presence of such a fluid. As such, they are utilized in connection with heating crank case oil in internal combustion engines by insertion of the immersion type heater through the oil lever measuring stick opening. Under these conditions, the heaters are subjected to rough usage such as dropping. Such shocks to the heaters will normally fracture the refractory materials included in the heater and occasionally expose the electrical conductors and heater coil to the metallic covering rendering the heater dangerous for usage. Further, the usage normally imparted to such apparatus requires that the immersion heater must be inserted through a relatively small hole in the chamber containing the fluid to be heated. In the insertion of the heater, stress is normally applied translationally to the extent of the heater. This stress creates a bending action which also produces fracture of the refractory insulating components within the heater. Modern automobiles also have varying and smaller sized dip stick openings. The improved heater design "has a small diametrical dimension of approximately A1 of an inch to permit it to fit into such small openings and as such have universal application in automobiles. The subject invention is an improvement over the design of the immersion type heater shown in the patent to George Grinde 2,508,512, dated May 23, 1950 and assigned to the assignee of the subject invention. The present immersion type heater design overcomes these problems in a simplified, small diameter, rugged and inexpensive heater design.

It is therefore the primary object of this invention to 1 provide an improved immersion type heater which has a small diameter and is extremely efficient, rugged in construction, and non-hazardous in application.

Another object of this invention is to provide in an immersion type heater, a simplified design which is relatively inexpensive to manufacture and has a long life.

These and other objects of this invention will become apparent from the reading of the attached description together with the drawings wherein:

FIGURE 1 is a schematic view in section of a container with fluid therein showing the application of the improved immersion type heater;

FIGURE 2 is an elevation'view in section of the improved immersion type heater;

FIGURE 3 is an enlarged sectional view of a portion of the improved immersion type heater of FIGURE 2; and

FIGURE 4 is an enlarged sectional view of another portion of the improved immersion type heater of FIG- URE 2.

This improved immersion type heater is shown generally in FIGURE 1 by the numeral 10, which includes ICC at 11 a crank case or similar container for a lubricant or a liquid, indicated at 12, with the immersion type heater inserted through an opening 13 in the container. In the case of the crank case for an internal combustion engine, the opening 13 would be the dip stick oil level measuring opening which stick (not shown) would be removed to permit the insertion of the heater for the purpose of warming the oil under abnormal low temperature conditions. The immersion type heater includes an insulated electrical conduit 15 with a suitable electrical connector 16 at the extremity thereof adapted to be connected to a source of electrical power. The heater when energized from the source of power, will provide a concentrical source of heat for the liquid to arise the temperature of the same to desired working temperature level for the fluid or oil in a conventional manner.

The improved immersion type heater is shown in section in FIGURE 2 as including an elongated tubular casing 20 which is closed at one extremity, as at 22, through suitable metal working methods, such as spinning or Welding, and open at the other extremity, as at 24. Casing 20 is a flexible metal tubing made of a high resistance steel, such as stainless steel, and I have found that such a tubular casing having an outside dimension of approximately one-quarter of an inch or an outside dimension of approximately .240 inch and an internal dimension of approximately .210 inch suitable for this purpose.

As will be seen in FIGURE 2, the tubular casing 20 is shown in cross-section and a first ceramic or refractory insulating member 25 which is tubular in form, is positioned abutting the closed extremity of the casing. Insulating member 25 has an outside diameter of approximately .190 inch to fit closely within the interior of the casing 20 for good heat transfer, as will be later noted. This refractory insulating member has a pair of passages 26, 27 having diameters of .060 inch approximately therein which are spaced apart and parallel to one another extending along the extent of the tube. The extremity of the tube adjacent the closed extremity of the casing 20 is notched, as at 28, such that the extremities of the passages 26, 27 are spaced from the closed extremity 22 of the casing 20. Positioned in the passages 26, 27 is a heater coil element 20, which element is made of a high resistance wire of small diametrical dimension or size. Heater coil element 30 is positioned snugly within the passages 26, 27 to be in good heat transfer relationship with the refractory insulating member and is bent at its mid-point to position this bend in the notch 28 of the refractory insulating member 25 and locate the halves of the heater coil element 30 in the passages 26, 27. These portions or halves of the heater coil element 30 terminate near the extremity of the refractory insulating member 25 remote from the notch 28 where they are connected to a pair of solid flexible conductor members 32, 33 (see FIGURE 3). The connection between the ends of the heater element and the conductors 32, 33 is made through suitable means, such as silver soldering, and the conductors 32, 33 are of considerably larger diameter than the Wire size of the heater coil element 30 and of proportionately less resistance. The heater coil element 30 can be made of any suitable material such as nichrome wire and the conductors 32, 33 are of the low resistance type to provide proper lead in conductors to the heater coil element 30.

The conductors 32, 33 pass through a second refractory insulating member 40 which similarly has a pair of passages 35, 36 therein aligned with the passages 26, 27 in the member 25 through which the conductors 32, 33 extend. These conductors are insulated only by these refractory insulating members 40 and the refractory insulating member 40 is of smaller diametrical dimension than the member 25 having an outside diameter of approximately .156 inch such that it does not engage the internal sides of the casing 20, but rather provides a clearance therebetween, for purposes to be later noted. The refractory insulating member 25 is accurately machined and ground to fit into the internal diameter or dimensions of the casing 20 at the closed extremity thereof such that it will fit snugly therein to provide a good heat transfer relationship with the casing and not be stressed by irregularities on the surface thereof. The ceramic member 25 with the heater therein covers slightly less than one-quarter of the entire casing and the member 40 positioned adjacent the same and covering the bare lead wires 32, 33 extends short of the mid-point of the casing member.

Beyond the ceramic member 40, the conductors 32, 33 are covered with a plastic or fiberglass covering 45 having a substantially lower combustion temperature than that of the insulating refractory members and the conductors 32, 33 so covered extend substantially to the open end 24 of the casing. Positioned in the open end of the cas ing is the insulated conduit which has external dimensions sufficient to fit telescopically into the open end 24 of the casing. Conductors 48 of the insulated conduit 15 extend beyond the covering of the insulated conduit 15 and are connected to the conductors 32, 33 through suitable means, such as soldering. The exposed ends of the conductors 32, 33 and the conductors 48 or lead in wires from the conduit 15 are covered by suitable insulating material 52 which is wrapped around the same to insulate these connections. Conduit 15 is also secured to the end -24 of the casing through suitable means such as crimping, indicated at 55, to rigidly secure the conduit 15 in the casing 20- and close the end of the casing.

The operation of the improved immersion type heater, from a heating standpoint, is conventional. Application of power to the heater coil element 30 through the connection of the insulated conduit 15 at the connector 16 to a power source will apply electrical cur-rent to the heater element to energize the same. This heater element is located in the lower one-quarter of the casing 20 so as to be positioned in the most effective location with respect to heating of the fluid in which the heater is immersed. The heater coil element 30 with the refractory insulating member provides an eflicient and effective heat source which is concentrated at the lower extremity of the casing and transfers heat through the stainless steel casing 20 to the fluid surrounding the same. The refractory insulating member 25 surrounding the heater also protects the same Within the casing and prevents the heater coil from shorting against the metallic casing. This refractory insulating member 25 is machined or finished to snugly fit into the casing to provide a good heat transfer to the casing 20; and provides a mounting of the heater coil element which will not be fractured due to expansion or con-traction under the variation of temperature applied to the same.

It is also snugly fit into the casing so as to withstand shock. The simplified notched structure at the end of the same spaces the heater coil element from the end of the end 22 of the casing 20 to provide an electrical insulation between the casing and the heater element at this point without the addition of any further insulating parts.

This immersion type heater is constructed to withstand rugged usage and the second refractory insulating member 40 which is spaced from the Walls of the casing member 20' protects the lead in conductors 32, 33 by providing an insulating covering over the same while at the same time, allowing for limited displacement of the casing relative to the conductors without danger of fracture to the refractory insulating member 40. The refractory insulating member 40 represents a low cost insulation which is an excellent heat buifer between the heater coil element and the plastic fiberglass type covering positioned over the conductors 32, 33 in the upper or opposite half of the immersion heater casing 20. These conductors are also spaced from the walls of the casing permitting limited freedom of movement or deflection of the casing relative to the assembly without danger of fracture of parts therein. The heat buffer insures that heat from the heater coil element will not chemically affect the fiberglass covering on the conductors to generate gas therefrom or cause deterioration of the insulation thereon. The seal in the end of the tube, while shown as crimp seal, may take other forms and the reduction of the heat created between the heater coil element and the opposite end of the casing also protects the materials forming the insulated conduit 15.

While this improved immersion type heater is ideally adapted for use in conjunction with oil crank cases in internal combusion engines, it obviously may be utilized for the warming of other fluids in similar containers. Its small diameter makes it universally applicable to all sizes and types of internal combusion engines having oil sumps. The simplicity in the design and the minimum and types of materials employed, reduces the cost 'of manufacture of the improved immersion type heater. Therefore, in considering this invention, its scope will be determined by the appended claims.

I claim:

'1. An immersion type heater comprising, an elongated tubular metallic casing closed at one extremity and opened at the other extremity, a high resistance coil heater element, an elongated refractory insulating member having a pair of spaced parallel passages extending longitudinally therethrough with a notched extremity, said heater coil element being positioned in said spaced parallel passages in said refractory insulating member and being bent at its midpoint to position the halves of said heater coil element in said respective passages, said notched extremity of said insulating member positioning the bend of said heater'coil element and spacing the bend of said heater coil element from the extremity of said insulating member, said insulating member with said heater coil element therein being positioned in the closed extremity of said casing and extending from said closed extremity substantially one-quarter of the extent of said casing, a pair of solid flexible conductors extending into said passages and connected to the ends of said heater coil element, a second refractory insulating member with a pair of spaced parallel passagestherein with said conductors extending through said passages, said second refractory insulating member being positioned to abut the end of said first named refractory insulating member and enclose said conductors and extend within said casing approximately a distance of less than one-quarter of the extent of said casing, a flexible insulated covering having a substantially lower combusion temperature than said refractory insulating member positioned over the conductors and extending from said second refractory insulating member short of the opening in the end of said casing, an insulated electrical conduit telescopically fitting into the open end of said casing and including lead in conductors connected to the ends of said solid conductors in said casing, insulation means covering the connections of said solid conductors with said lead in conductors, and means included in part in said casing securing said insulated electrical conduit in the end of said casing to close the same.

2. An immersion type heater comprising, an elongated tubular metallic casing closed at one extremity and opened at the other extremity, a high resistance coil heater element, an elongated refractory insulating member having a pair of spaced parallel passages extending longitudinally therethrough, said heater coil element being positioned in said spaced parallel passages in said refractory insulating member being bent at its midpoint to position the halves of said heater coil element in said respective passages, said insulating member with said heater coil element therein being positioned in the closed extremity of said casing and fitting snugly within said casing in good heat transfer relationship therewith, a pair of solid flexible conductors extending into said passages and connected to the ends of said heater coil element, a second refractory insulating member with a pair of spaced parallel passages therein with said conductors extending through said passages, said second refractory insulating member being of substantially lesser diametrical dimension than the interior dimension of said casing and the exterior dimension of said first named refractory insulating member and being positioned to abut the end of said first named refractory insulating member and en close said conductors, a flexible insulated covering positioned over the conductors and extending from said second refractory insulating member short of the opening in the end of said casing, an insulated electrical conduit including lead in conductors connected to the ends of said solid conductors in said casing, insulation means covering the connection of said solid conductors and said insulated conductors positioned in the open end of said casing, and means included in part in said casing securing said insulated electrical conduit to the end of said casing to close the same.

3. The immersion type heater of claim 1 in which the conductor wire diameter is appreciably larger than and of lower conductivity than the wire of said heater coiled element.

4. The immersion type heater of claim 1 in which the first named refractory insulating member is ground on its external surface to smoothly and snugly fit into the interior of said casing.

5. The immersion type heater of claim 2 in which the second refractory insulating member acts as a heat conductivity buffer between said heater coil element and the covering on said conductors as well as the insulated electrical conduit in the open end of said casing.

6. The immersion type heater of claim 5 in which the casing may be flexed over substantially three-quarters of its extent from the opened end thereof without damage to said refractory members.

7. The immersion type heater of claim 6 in which the flexible and insulating covering positioned on the conductors is comprised of a fiberglass material.

8. The immersion type heater of claim 7 in which the .outside dimension of said casing is approximately onequarter of an inch.

9. An immersion type heater comprising, an elongated tubular metallic casing closed at one extremity and opened at the other extremity, a high resistance coil heater element, an elongated refractory insulating member having a pair of spaced parallel passages extending longitudinally therethrough with a notched extremity, said heater coil element being positioned in said spaced parallel passages in said refractory insulating member and being bent at its midpoint to position the halves of said heater coil element in said respective passages, said notched extremity of said insulating member positioning the bend of said heater coil element and spacing the bend of said heater coil element from the extremity of said insulating member, said insulating member with said heater coil element therein being positioned in the closed extremity of said casing and extending from said closed extremity substantially one-quarter of the extent of said casing, a pair of solid flexible conductors extending into said passages and connected to the ends of said heater coil element, a sec-- ond refractory insulating member with a pair of spaced parallel passages therein with said conductors extending through said passages, said second refractory insulating member being of substantially lesser diametrical dimension than the interior dimension of said casing and the exterior dimension of said first named refractory insulating member and being positioned to abut the end of said first named refractory insulating member and enclose said conductors to extendwithin said casing approximately a distance of less than one-quarter of the extent of said casing, a flexible insulated covering positioned over the conductors and extending from said second refractory insulating member short of the opening in the end of saidcasing, an insulated electrical conduit telescopically fitting into the open end of said casing and including lead in conductors connected to the ends of said solid conductors in said casing, and means included in part in said casing securing said insulated electrical conduit in the end of said casing to close the same.

10. An immersion type heater comprising, an elongated tubular metallic casing closed at one extremity and opened at the other extremity, a high resistance coil heater element, an elongated refractory insulating member having a pair of spaced parallel passages extending longitudinally therethrough, said heater coil element being positioned in said spaced parallel passages in said refractory insulating member and being bent at its midpoint to position the halves of said heater coil element in said respective passages, means included in the extremity of said insulating member positioning the bend of said heater coil element and spacing the bend of said heater coil element from the extremity of said insulating member, said insulating member with said heater coil element therein being positioned in the closed extremity of said casing, a pair of solid flexible conductors extending into said passages and connected to the ends of said heater coil element, a second refractory insulating member with a pair of spaced parallel passages therein with said conductors extending through said passages, said second refractory insulating member being of lesser diametrical dimension than the interior dimension of said casing and the exterior dimension of said first named refractory insulating member and being positioned to abut the end of said first named refractory insulating member and enclose said conductors, a fiberglass insulating covering having a substantially lower combustion temperature than said refractory References Cited by the Examiner v UNITED STATES PATENTS 1,394,518 10/1921 Abbott 338-239 2,508,512 5/1950 Grinde 338-229 2,629,041 2/1953 Fein et a1 219-205 X 2,728,832 12/1955 Hoffman 338-229 X 2,766,367 10/ 1956 Chaustowich 338-229 X 2,912,664 11/1959 Kinney 338-229 3,171,015 2/1965 Grinde 219-205 RICHARD M. WOOD, Primary Examiner. V. Y. MAYEWSKY, Assistant Examiner. 

1. AN IMMERSION TYPE HEATER COMPRISING, AN ELONGATED TUBULAR METALLIC CASING CLOSED AT ONE EXTREMITY AND OPENED AT THE OTHER EXTREMITY, A HIGH RESISTANCE COIL HEATER ELEMENT, AN ELONGATED REFRACTORY INSULATING MEMBER HAVING A PAIR OF SPACED PARALLEL PASSAGES EXTENDING LONGITUDINALLY THERETHROUGH WITH A NOTCHED EXTREMITY, SAID HEATER COIL ELEMENT BEING POSITIONED IN SAID SPACED PARALLEL PASSAGES IN SAID REFRACTORY INSULATING MEMBER AND BEING BENT AT ITS MIDPOINT TO POSITION THE HALVES OF SAID HEATER COIL ELEMENT IN SAID RESPECTIVE PASSAGES, SAID NOTCHED EXTREMITY OF SAID INSULATING MEMBER POSITIONING THE BEND OF SAID HEATER COIL ELEMENT AND SPACING THE BEND OF SAID HEATER COIL ELEMENT FROM THE EXTREMITY OF SAID INSULATING MEMBER, SAID INSULATING MEMBER WITH SAID HEATER COIL ELEMENT THEREIN BEING POSITIONED IN THE CLOSED EXTREMITY OF SAID CASING AND EXTENDING FROM SAID CLOSED EXTREMITY SUBSTANTIALLY ONE-QUARTER OF THE EXTENT OF SAID CASING, A PAIR OF SOLID FLEXIBLE CONDUCTORS EXTENDING INTO SAID PASSAGES AND CONNECTED TO THE ENDS OF SAID HEATER COIL ELEMENT, A SECOND REFRACTORY INSULATING MEMBER WITH A PAIR OF SPACED PARALLEL PASSAGES THEREIN WITH SAID CONDUCTORS EXTENDING THROUGH SAID PASSAGES, SAID SECOND REFRACTORY INSULATING MEMBER BEING POSITIONED TO ABUT THE END OF SAID FIRST NAMED REFRACTORY INSULATING MEMBER AND ENCLOSE SAID CONDUCTORS AND EXTEND WITHIN SAID CASING APPROXIMATELY A DISTANCE OF LESS THAN ONE-QUARTER OF THE EXTENT OF SAID CASING, A FLEXIBLE INSULATED COVERING HAVING A SUBSTANTIALLY LOWER COMBUSION TEMPERATURE THAN SAID REFRACTORY INSULATING MEMBER POSITIONED OVER THE CONDUCTORS AND EXTENDING FROM SAID SECOND REFRACTROY INSULATING MEMBER SHORT OF THE OPENING IN THE END OF SAID CASING, AN INSULATED ELECTRICAL CONDUIT TELESCOPICALLY FITTING INTO THE OPEN END OF SAID CASING AND INCLUDING LEAD IN CONDUCTORS CONNECTED TO THE ENDS OF SAID SOLID CONDUCTORS IN SAID CASING, INSULATION MEANS COVERING THE CONNECTIONS OF SAID SOLID CONDUCTORS WITH SAID LEAD IN CONDUCTORS, AND MEANS INCLUDED IN PART IN SAID CASING SECURING SAID INSULATED ELECTRICAL CONDUIT IN THE END OF SAID CASING TO CLOSE THE SAME. 